1. Field of the Invention
The present invention relates to output planning management, and particularly to a computer implemented system and method of control factor management in a production system.
2. Description of the Related Art
In recent years, many enterprises or manufacturers have introduced the concept of “supply chain” to integrate their internal and external resources. The supply chain considers functions of purchase of materials, transformation of these materials into intermediate and finished products, and the distribution of these finished products to customers. Supply chains exist in most manufacturing environments, although the complexity of the chain may vary greatly from industry to industry and firm to firm. For integrated circuit (IC) foundries, the manufacturing process of each IC product is complicated and varies and the cost of wafers and capacity is relatively high.
In the supply chain, customers transmit requests (demands) consisting of a request for a particular quantity of a product by a specific date to a manufacturer, and the manufacturer plans its manufacturing schedule according to these received requests to satisfy each customer. After the order is taken, it is important for manufacturing systems to deliver products for clients on time. Therefore, the delivery date becomes crucial to assure clients when they can receive the product they ordered.
Many commercial supply chain solution providers provide packaged systems for clients to install and follow, such as i2 Inc. of Springfield Va. or ADEXA Inc. of Los Angeles Calif. (ADEXA is a registered trademark of ADEXA Inc.) For a manufacturer or a factory, a production scheduling engine is usually embedded in the systems to arrange resources and materials for a production plan. The production scheduling engines provide a master production schedule (MPS) as the production target for the manufacturer or factory to follow.
For conventional supply chain, delivery dates for products are designed to be estimated according to a customized algorithm that introduces critical factors of the manufacturing system. More specifically, the critical factors, i.e. the “control factors,” of the customized algorithm are usually bottleneck factors for the manufacturing system. A forecasted result, i.e. a forecasted delivery date, can be obtained by the algorithm with the control factors determined. Accordingly, the control factors serve as a key input parameter of the production scheduling engines.
However, for the purpose of management in a manufacturing system, it is a dilemma to meet both the future production target and the forecasted results of current actual production. In a production system, e.g. an IC foundry, a cycle time for the IC product is generally applied as the control factor of the production scheduling engine, i.e. a plan engine 130 as shown in FIG. 1. The plan engine 130 generates a production schedule, i.e. a plan, for a work-in-process (WIP) 110 in the production system 150 based on the WIP 110 and the reserved capacity 120 for the WIP 110. The cycle time (the control factor) is determined by the planner and input to the plan engine 130 via a user interface 140.
When the cycle time is set to approach the current actual cycle time, accuracy of the forecasted delivery date increases, but the delivery date target requested by the client may be delayed. On the other hand, when the cycle time is set to meet the delivery date target, production can be improved to achieve the request of the client, but the quality and accuracy of the forecasted delivery date is unavoidably impacted. Generally, the planner determines the control factor to a fixed value by experience as a compromise between the future production target and the forecasted results of current actual production. There is no effective method for the planner to determine the control factor.